In such machines, the sinkers are movably supported in the longitudinal direction of the needles and controlled such that they are moved at a given feed after locking in of the yarn counter to the pull-off direction of the associated needles and after knocking over of the loop counter to the needle raising direction. The needle cam curve and the sinker cam curve have adjoining, steadily curved arc portions; in the case of the needle cam these portions are sinusoidal and merge smoothly, or steplessly, with one another.
Knitting machines in which the locking-in and knockover sinkers are controlled in the longitudinal direction of the needles contrary to the direction of needle movement make it possible to attain a very high knitting speed while producing goods of excellent quality. This is because the paths of movement of the needles are relatively short, and so the associated needle cam curves can have correspondingly little slope. To prevent abrupt impacts on the latch needles as much as possible and to prevent transmitting vibration to them, the use of a needle cam curve that comprises steadily curved, sinusoidal arc portions that merge steplessly with one another is known from German Patent DE-PS No. 31 08 041. Thus especially in the areas of their motion reversal points the needles are accelerated or decelerated particularly gently, which reduces the stress on the needles caused by impact waves accordingly.
The sinker cam curve of this known knitting machine is also made up of steadily curved arc portions, but they are connected to one another by arc portions having a shorter radius of curvature, and so the overall result is an undulating sinker cam curve. This shape of the sinker cam curve is the product of the realization that the sinkers together with the needles, over the length of the new loop that has been drawn through the old loop, should hold the just-formed loops over at least two adjacent needle slots, and to do so the needles and sinkers must then execute a pull-off movement in the same direction up to the maximally lowered height of the sinkers. Since the reversal of the sinkers in the region of draw-through of the new loop must be effected relatively fast, because during this time the needles are continuing their lowering movement uninterruptedly, the radius of curvature of the arc portions of the sinker cam having the shorter radius of curvature is necessarily relatively short. Although the acceleration which the sinkers undergo in this reversal is substantially less than that occurring with sinker curves having angles or other irregularities, still the peaks of acceleration that occur at very high knitting speeds can make themselves apparent in the form of increased noise. This noise, however, is again associated with wear.